Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$117.25	5.702%	$123.9356	$123.94	$123.95	$123.90
Purchase #2	$67.73	4.637%	$70.8706	$70.87	$70.85	$70.90
Purchase #3	$156.69	9.837%	$172.1036	$172.10	$172.10	$172.10
Purchase #4	$145.46	4.276%	$151.6799	$151.68	$151.70	$151.70
Purchase #5	$93.32	5.152%	$98.1278	$98.13	$98.15	$98.10
Purchase #6	$121.85	5.352%	$128.3714	$128.37	$128.35	$128.40
Purchase #7	$250.83	6.496%	$267.1239	$267.12	$267.10	$267.10
7 purchase totals =	$953.13		$1,012.2128	$1,012.21	$1,012.20	$1,012.20